1. Field of the Invention
The present invention relates to a printing system constituted by a host unit and a print output apparatus for performing printing of print data supplied from the host unit.
2. Related Background Art
Conventionally, print output apparatuses (hereinafter referred to as a printer) in information processing systems form images by fixing toner, ink or the like on paper, etc. For example, laser beam printers and copying machines have a mechanism for fixing toner on paper by heating a thermal transfer drum portion.
Some laser beam printers require electric power of, for example, about 765 W for printing (heating). Such high electric power is required because of the need to heat the thermal transfer drum portion to a high temperature and to rapidly heat the drum to a temperature at which printing can be performed. If the heating time period is reduced, the time period taken to start printing is reduced. That is, it is possible to increase the overall printing speed by reducing the heating time period.
A technique has therefore been used in a printer which sets a printer in a standby state in which the thermal transfer drum portion is constantly maintained at a temperature close to the high temperature at which printing can be performed. The technique enables the printer to start printing immediately after receiving the print data and to always perform high-speed printing if the frequency of use of the printer is high.
However, if the frequency of use of the printer is low, a large amount of electric power consumed in the standby state (e.g., about 183 W) is wasted. For this reason, a technique has been used in many printers which sets the state of the printer to be shifted from the standby state to a sleep state in which power consumption is automatically limited in the case where the printer is maintained in the standby state without being used during certain time period. More specifically, when the printer is shifted to the sleep state, the temperature at which the thermal transfer drum portion is kept is reduced or the heat-retention is stopped. For example, the power consumption in the sleep state is about 22 W and there is an effect of reducing the power consumption by 161 W compared to that of the standby state.
A technique has also been used which automatically performs processing for shifting to the standby state, including heating the thermal transfer drum portion, when the print data is received in the sleep state.
As described above, the conventional printers are designed so as to operate selectively in the standby state or the sleep state, thereby achieving both high-speed printing in a situation where the frequency of use is high and an economical effect in a situation where the frequency of use is low.